Well you can check which IP are in use using nmap

sudo nmap -sP -PR 212.122.161.*

It will scan entire /24 and show results

Device eth0 does not seem to be present, delaying initialization” Error’

Was getting this error after migrating centos 6 VM to new host

The best way to fix this isssue was deleting file rm /etc/udev/rules.d/70-persistent-net.rules

and rebooting vm.. Network was up and issue fixed